On the computation of Hopf 2-cocycles with an example of diagonal type.

Autor: García Iglesias, Agustín, Sánchez, José Ignacio
Předmět:
Zdroj: Glasgow Mathematical Journal; Jan2023, Vol. 65 Issue 1, p141-169, 29p
Abstrakt: We present a framework for the computation of the Hopf 2-cocycles involved in the deformations of Nichols algebras over semisimple Hopf algebras. We write down a recurrence formula and investigate the extent of the connection with invariant Hochschild cohomology in terms of exponentials. As an example, we present detailed computations leading to the explicit description of the Hopf 2-cocycles involved in the deformations of a Nichols algebra of Cartan type $A_2$ with $q=-1$ , a.k.a. the positive part of the small quantum group $\mathfrak{u}^+_{\sqrt{-\text{1}}}(\mathfrak{sl}_3)$. We show that these cocycles are generically pure , that is they are not cohomologous to exponentials of Hochschild 2-cocycles. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index